Heteroaromatic phthalonitriles

ABSTRACT

Disclosed are an oligomer and a phthalonitrile monomer having the formulas: 
     
       
         
         
             
             
         
       
     
     M is a metal or H. The value n is an integer greater than or equal to 1 for the oligomer and greater than or equal to 0 for the phthalonitrile monomer. Ar 1  and Ar 2  are independently selected aromatic- or heterocyclic-containing groups. Ar 1 , Ar 2 , or both are heteroaromatic or heterocyclic groups containing a nitrogen, sulfur, or oxygen heteroatom. Also disclosed are thermosets and pyrolyzed materials made from the phthalonitrile monomer.

This application is a divisional application of U.S. patent applicationSer. No. 12/616,836, allowed and filed on Nov. 12, 2009.

TECHNICAL FIELD

The present disclosure is generally related to oligomers containingheteroaromatic groups and phthalonitriles, thermosets, and othermaterials made therefrom.

DESCRIPTION OF RELATED ART

Phthalonitrile resins show potential as matrix materials for advancedcomposites. The phthalonitrile monomers polymerize through the cyanogroups with the aid of an appropriate curing agent to yield acrosslinked polymeric network with high thermal and oxidativestabilities. These polymers are obtained by heating the phthalonitrilemonomers and a small amount of curing additive in the melt-state above200° C. for extended periods of time. Phthalonitrile monomers andphthalonitrile polymers of various types are described generally in U.S.Pat. No. 3,730,946, U.S. Pat. No. 3,763,210, U.S. Pat. No. 3,787,475,U.S. Pat. No. 3,869,499, U.S. Pat. No. 3,972,902, U.S. Pat. No.4,209,458, U.S. Pat. No. 4,223,123, U.S. Pat. No. 4,226,801, U.S. Pat.No. 4,234,712, U.S. Pat. No. 4,238,601, U.S. Pat. No. 4,259,471, U.S.Pat. No. 4,304,896, U.S. Pat. No. 4,307,035, U.S. Pat. No. 4,315,093,U.S. Pat. No. 4,351,776, U.S. Pat. No. 4,408,035, U.S. Pat. No.4,409,382, U.S. Pat. No. 4,410,676, U.S. Pat. No. 5,003,039, U.S. Pat.No. 5,003,078, U.S. Pat. No. 5,004,801, U.S. Pat. No. 5,132,396, U.S.Pat. No. 5,159,054, U.S. Pat. No. 5,202,414, U.S. Pat. No. 5,208,318,U.S. Pat. No. 5,237,045, U.S. Pat. No. 5,242,755, U.S. Pat. No.5,247,060, U.S. Pat. No. 5,292,854, U.S. Pat. No. 5,304,625, U.S. Pat.No. 5,350,828, U.S. Pat. No. 5,352,760, U.S. Pat. No. 5,389,441, U.S.Pat. No. 5,464,926, U.S. Pat. No. 5,925,475, U.S. Pat. No. 5,965,268,U.S. Pat. No. 6,001,926, U.S. Pat. No. 6,297,298, U.S. Pat. No.6,756,470, U.S. Pat. No. 6,891,014, U.S. Pat. No. 7,452,959, U.S. Pat.No. 7,511,113, and U.S. Pat. Appl. Pub. Nos. 2008/0255287 and2009/0069484 (all publications and patent documents referencedthroughout this application are incorporated herein by reference.)

Previously, a variety of phthalonitrile monomers containing aromaticether, thioether, imide and sulfone linkages between the terminalphthalonitrile units have been synthesized and cured or converted tocrosslinked/networked polymers. The cure reaction of these monomers hasbeen investigated by a variety of curing additives such as organicamines, strong organic acids, strong organic acids/amine salts, metallicsalts and metals. When post-cured at elevated temperatures to about 400°C., the thermoset shows excellent long-term thermal and oxidativestabilities to temperatures approaching 375° C. In addition, the higharomatic content of the thermoset affords a high char yield (80-90%)when pyrolyzed to 1000° C. under inert conditions. The high thermalstability and the ability to form a high char yield upon pyrolysiscontribute to the outstanding fire performance of the phthalonitrilepolymer. For instance, the fire performance of phthalonitrile-carbon andphthalonitrile-glass composites are superior to that of otherthermoset-based composites currently in use for aerospace, ship andsubmarine applications. The phthalonitriles are the only polymericmaterial that meets MIL-STD-2031 for usage inside of a submarine and arebeing considered for usage below deck on warships.

High performance polymers have been converted into carbon nanotube andcarbon nanotube-metal nanoparticle compositions. The approach is thatshaped solid components, fibers, and films can be fabricated from themelt or amorphous state of the precursor compounds. Moreover, theresulting polymer or charred materials containing elemental Fe, Ni,and/or Co nanoparticles dispersed throughout the polymeric and carbondomains exhibit magnetic properties (attracted to a bar magnet). Themagnetic and electrical properties in these systems can be fine-tuned asa function of heat treatment, time, and temperature. Broad methods forthe synthesis of the various carbon nanotube and carbon nanotube-metalnanoparticle compositions from commercially available resins and highperformance polymers are disclosed in U.S. Pat. No. 6,770,583, U.S. Pat.No. 6,846,345, U.S. Pat. No. 7,579,424, and U.S. Pat. Appl. Pub. Nos.2006/0130609 and 2008/0255287. Moreover, materials (polyacrylonitrileand the pitches) that are presently being used to fabricate commercialcarbon and graphitic fibers can be converted into carbon nanotube andcarbon nanotube-metal nanoparticle containing fibers. Magnetic carbonnanotube fibers have been realized for potential electrical and magneticdevice applications. Phenolic resins (an inexpensive source of carbon)can be converted into a carbon nanotube carbonaceous composition. Highperformance and high temperature polymers such as the polyimides,epoxies, phthalonitriles, cyanate ester resins, polyaryletheretherketone(PEEK), and polyaromaticsulfones (PES) are commercially available andcan be used in the formulation of a bulk solid, fiber, and/orfilm-containing carbon nanotube composition. Depending on theformulation parameters, the physical properties can be varied forpotential magnetic, electrical, structural, catalytic, and medicalapplications. The approach allows for the in situ formation of metalnanoparticles and carbon nanotubes-metal nanoparticles within a highperformance polymeric system and carbonaceous composition, respectively.The ability to control the amount and size of the metal nanoparticleswithin the polymeric and carbon nanotube composition can be achieved.Control of the carbon nanotube and metal nanoparticle concentration isimportant for various potential applications. Upon gelation, themobility of the metal particles will be reduced and the metal particleswill be less free to move within the developing solid composition.Besides Fe, Ni, and Co systems, it is believed that any transition metalsalt, organometallic compound, or metal alloy that decomposes into metalatoms such as Ru, Os, Mo, W, etc., can be used as the metal source forthe formation of carbon nanotubes.

BRIEF SUMMARY

Disclosed herein is an oligomer having the formula:

M is a metal or H. The value n is an integer greater than or equal to 1;Ar¹ and Ar² are independently selected aromatic- orheterocyclic-containing groups; and Ar¹, Ar², or both are heteroaromaticor heterocyclic groups containing a nitrogen, sulfur, or oxygenheteroatom.

Also disclosed herein is a phthalonitrile monomer having the formula:

The value n is an integer greater than or equal to 0 and Ar¹ and Ar² areindependently selected aromatic- or heterocyclic-containing groups. If nis greater than 0, then Ar¹, Ar², or both are heteroaromatic orheterocyclic groups containing a nitrogen, sulfur, or oxygen heteroatom.If n is 0, then Ar¹ is a heteroaromatic or heterocyclic group containinga nitrogen, sulfur, or oxygen heteroatom.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention will be readily obtainedby reference to the following Description of the Example Embodiments andthe accompanying drawings.

FIG. 1 shows a DSC of the phthalonitrile of Example 1 heated with 5%p-BAPS.

FIG. 2 shows a DSC of the phthalonitrile of Example 19 heated with 5%p-BAPS.

FIG. 3 shows a XRD showing the presence of CNTs/CNFs in a sample of thenitrogen heteroaromatic-containing phthalonitrile of Example 1 heated to1000° C. in the presence of Fe₂(CO)₉.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

In the following description, for purposes of explanation and notlimitation, specific details are set forth in order to provide athorough understanding of the present disclosure. However, it will beapparent to one skilled in the art that the present subject matter maybe practiced in other embodiments that depart from these specificdetails. In other instances, detailed descriptions of well-known methodsand devices are omitted so as to not obscure the present disclosure withunnecessary detail.

Disclosed are methods related to the synthesis and polymerization ofheteroaromatic- and heterocyclic-containing phthalonitriles and lowmelting oligomeric heteroaromatic and/or heterocyclic-containingphthalonitriles in which the nitrogen, oxygen, and/or sulfurheteroaromatic and/or heterocyclic moieties or linkages are situatedbetween the terminal phthalonitrile units, their conversion to hightemperature thermosets, and the thermal treatment and carbonization tocarbon nanotube-containing carbonaceous solids. The simpleheteroaromatic-and heterocyclic-containing phthalonitriles aresynthesized from the corresponding dihydroxyl heteroaromatic orheterocyclic compounds. The oligomeric heteroaromatic- and/orheterocyclic-containing phthalonitriles are synthesized from thecorresponding oligomeric dihydroxyl-terminated compounds. The nitrogen,oxygen, and/or sulfur heteroaromatic- and/or heterocyclic-containingphthalonitrile monomers upon polymerization to thermosets may showsuperior thermal, thermo-oxidative, and flammability properties and canwithstand continuous high temperatures (300-375° C.) in an oxidativeenvironment such as air for extended periods. To date, currentoligomeric phthalonitrile polymers have melting points between 50 and260° C. with the polymerization occurring in excess of 200° C. The useof oligomeric heteroaromatic- and heterocyclic-containingphthalonitriles, which melt at relative low temperatures, to obtainthermosetting polymeric materials with high thermo-oxidative propertiesmay be advantageous from a processing standpoint. Precursor resins areuseful in composite fabrication by a variety of methods such asinfusion, resin transfer molding, and prepreg consolidation. Thephthalonitriles may be useful for numerous aerospace and electronicapplications due to their thermal and oxidative properties,processability, and low water absorption relative to other hightemperature polymers such as polyimides. Furthermore, resins with alarge window between the melting point and the cure temperature may bedesirable to control the viscosity and the rate of curing. With thephthalonitrile monomers disclosed herein, processability to shapedcomposite components may be achieved in non-autoclave conditionspotentially above 70° C. and by cost effective methods; the nitrogen,oxygen, and sulfur heteroaromatic and heterocyclic based phthalonitrilesmay show enhanced adhesive properties. By incorporating heteroaromaticsand/or heterocyclics into the backbone or the interconnecting moietybetween the terminal phthalonitrile units, the adhesive properties ofthe high temperature thermoset may be enhanced relative to an aromaticsystem containing only carbon.

Also disclosed is the formation of the thermoset in the presence of asmall quantity of an organometallic compound and/or metal salt followedby thermal treatment to temperatures at least to, for example, 1300° C.in an inert atmosphere resulting in the formation of nitrogen, oxygen,and/or sulfur-containing carbon nanotubes (CNTs) and/or carbonnanofibers (CNFs) embedded in a carbonaceous solid matrix. The key tothe formation of the CNTs/CNFs is the decomposition of theorganometallic compound or metal salt into metal nanoparticles, whichinteract with the developing fused, heteroaromatic and/or heterocyclicring system during the polymerization and carbonization processes. Theheteroaromatic/heterocyclic precursor phthalonitrile materials areeither physically mixed or coated in solution with organometalliccompounds or metal salts that decompose upon thermal treatmentultimately yielding metal nanoparticles. The resulting metalnanoparticle compositions upon heating to temperatures above 500° C. mayafford CNT/CNF-metal nanoparticle compositions. The amount of CNTs/CNFsand metal nanoparticles depends on the temperature exposure andconcentration of metal nanoparticles, respectively. Carbon nanotubefibers and composite matrices can be formulated by the method of thisinvention. Precursor organometallic or metal salts to Fe, Ni, and Cohave been used in our studies. However, any transition metal that hasbeen shown to lead to the formation of CNTs from organic vapors, thermaldeposition of hydrocarbons, and arc discharge can probably be used toform an organometallic precursor with the phthalonitriles of thisinvention followed by thermal decomposition of the metallic ororganometallic unit to metal nanoparticles and formation of carbonnanotubes in the bulk of polymeric and carbon systems, respectively.Depending on the conditions, CNTs/CNFs will form either in amorphouscarbon or in a highly ordered graphitic domain. Films, fibers, andshaped components can be obtained. Carbon nanotube fibers may be madefrom inexpensive precursors that are presently being used to spincommercial fibers. The CNT/CNF compositions contain metal nanoparticlesin varying amounts depending on the original organometallicconcentration or metal salt in the precursor heteroaromatic and/orheterocyclic phthalonitriles. Moreover, the CNT/CNF compositions exhibitmagnetic and electrical properties, which can be fine-tuned. The methodcan allow for the formation in situ of nitrogen, oxygen, and/orsulfur-containing carbon nanotubes in a carbonaceous solid matrix. Thematerials can potentially be useful for structural, air filtration,microelectronic, battery, fuel cell electrode, hydrogen storage, andcatalytic applications. X-ray diffraction studies show that CNTs and/orCNFs are being formed in the carbonaceous media and their concentrationwill depend on the thermal exposure condition.

To enhance the uptake of gaseous materials, the incorporation ofheteroatoms such as nitrogen, oxygen, and/or sulfur into the CNTs/CNFsmay disrupt the aromaticity of a pure CNT or CNF and enhance the uptakeof gaseous materials such as hydrogen and toxins. The ability to storehydrogen in large quantities in lightweight materials is desirable forfuel cells for automobiles and other vehicles. A low melt viscosityphthalonitrile resin enables the large-scale production of shapedCNT/CNF-containing carbonaceous components. Low melting oligomericphthalonitrile monomers and curing additives (metal carbonyl and othermetal salts) have been shown to enhance the overall physical propertiesand processability of phthalonitriles.

The syntheses of example simple heteroaromatic- andheterocyclic-containing phthalonitriles are shown below (Eq. (1)nitrogen containing heteroaromatic; Eq. (2) sulfur containingheterocyclic). As used herein heteroaromatic and heterocyclic refers toany aromatic or cyclic compound in which at least one ring carbon atomis changed to a nitrogen, oxygen, or sulfur atom. The rings may bysubstituted or unsubstituted and contain single rings or multiple fusedor nonfused rings. Heteroaromatics and heterocyclics may be referred tocollectively as “heteroaromatics” for simplicity. The term “aromatic”may also include heteroaromatics. In the reactions shown below, aheteroaromatic diol is reacted with 4-nitrophthalonitrile to form thephthalonitrile-terminated monomer. The reaction may be performed in thepresence of a potassium carbonate catalyst. Other carbonates or basesmay be used, as may any method disclosed in the above-referencedphthalonitrile patents.

The low melting oligomeric heteroaromatic- and/orheterocyclic-containing phthalonitriles can exhibit a larger processingwindow useful for composite and device fabrication. The synthesis ofsuch oligomers is shown in Eq. (3). The term “oligomeric” means thatmore than one compound is formed during the synthesis of 1 with theaverage molecular weight dependent on the ratios of reactants, 2 and 3,used. The diol and dihalo may be reacted in the presence of a coppercompound and a base or by other methods known in the art, such as thosedisclosed in the above-referenced patents. An excess of diol is used sothat the intermediate may be terminated as the metal salt of a diol,where n is 1, 2, or more.

The synthesis of a series of oligomeric heteroaromatic- and/orheterocyclic-containing phthalonitriles 1, which contain nitrogen,oxygen, and/or sulfur atom(s) unit in the backbone or interconnectingunit between the terminal phthalonitriles, may be achieved, for example,by a modified Ullmann synthesis. The potassium diphenolate-terminatedintermediate was prepared from the reaction of 2 and 3 in the presenceof potassium carbonate as the base and a copper (I) complex in aDMF/toluene solvent mixture. This allows the azeotropic distillation ofthe water formed as a by-product in the reaction at temperatures between135 and 145° C. When no more water is observed being azeotropicallydistilled and infrared (IR) spectroscopy confirms the desired oligomericproduct, the reaction may be considered complete. Further reaction ofthe potassium diphenolate-terminated intermediate with4-nitrophthalonitrile 4 can afford the oligomeric phthalonitriles 1 in90-95% yields, which may be readily soluble in common organic solventssuch as toluene, DMF, acetone, methylene chloride, ether, andchloroform. The structures of the monomers 1 were confirmed by IR and¹1-1-NMR spectroscopy. The length of the spacer between the terminalphthalonitrile groups can be varied by changing the ratio between 2(excess) and 3. Oligomeric phthalonitrile resins 1 (n 1) generally havemelting points between 70 and 100° C., whereas the simple phthalonitrile(n=0) may have a melting point greater than 250° C. Severalheteroaromatic and heterocyclic phthalonitriles 1 have been synthesizedby this method and the structures are shown below.

The phthalonitriles may be cured to a thermoset. The thermoset willgenerally be made from a range of oligomer sizes having different valuesof n, but may be described by the average value of n. For example, a 3:2ratio of diol to dihalo will produce an n of 2, though longer andshorter oligomers may be present. An aromatic amine may be used as acuring agent, or any curing agent disclosed in the above-referencedphthalonitrile patents. The curing may also be done after combining themonomer with a filler, including but are not limited to, carbonnanotubes, hydrated aluminum silicate, carbon nanofibers, zinc oxide, orboric acid.

The nitrogen, oxygen, and sulfur heteroaromatic-containingphthalonitriles may be converted to a CNT- and/or CNF-containingcarbonaceous solid by heating the phthalonitrile in the presence of asmall quantity of a metal salt such as Fe₂(CO)₉, Ni(cyclooctadiene)₂(Ni(COD)₂), or Co₂(CO)₈ resulting in initially curing to the thermosetfollowed by thermal treatment to elevated temperatures where CNT/CNFformation readily occurs during carbonization above 700° C. CNTs may beformed when magnetic nanoparticles are formed. The typical experimentsare as follows: (1) the precursor materials and various amounts of ametal salt are mixed in methylene chloride or hexane with stirringfollowed by concentration to dryness, or (2) the precursor materials andvarious amounts of an organometallic compound or metal salt arethoroughly mixed physically in a solid composition. The compositionsformulated by either of the two methods are heated to varioustemperatures up to, for example, 1300° C. The organometallic compound ormetal salt decomposes resulting in the formation of metal atoms,clusters, and/or nanoparticles, which are responsible for thedevelopment and formation of the carbon nanotubes. The properties of thecarbon nanotube-metal nanoparticle composition will depend on the heattreatment, time of thermal exposure, and concentration of metalparticles.

Heat treatment of the phthalonitrile precursor-metal systems under inertconditions at 300-500° C. may result in the formation of elemental metal(Fe, Ni, and Co) in an insulating polymeric matrix as determined by theattraction of the composition to a magnet. The magnetic compositions mayretain excellent structural integrity. The polymers may also exhibithigh thermal stability. Upon polymerization, the useful thermalproperties (300-375° C.) exhibited by the phthalonitrile polymers may beretained. The different polymers with various concentrations of metalparticle sizes will have distinct properties, which would be expected toaffect the characteristics of the final metal containing systems.

Depending on the heteroaromatic and/or heterocyclic phthalonitrileprecursor system and application, fibers, films, powders, and matrixcomponents can be formulated by the method. The metal nanoparticle,carbon nanotube, carbon nanofiber, and carbon nanotube-metalnanoparticle compositions could have novel magnetic, electrical,catalytic, and structural properties.

Only metal nanoparticles that are generated in situ and chemicallyinteract with the precursor organic materials during the heat treatmentcan be used to form the nitrogen, oxygen, and/orsulfur-containing-CNTs/CNFs within the charred carbonaceouscompositions. The amount of nitrogen, oxygen, and/or sulfur incorporatedinto the CNT carbonaceous solids will depend on the precursorphthalonitrile and the char yield. The metal nanoparticle size andconcentration can be readily changed by varying the concentration ofprecursor heteroaromatic and/or heterocyclic phthalonitrile andorganometallic compound or metal salt. Metals that are not magneticafford metal nanoparticles embedded within the carbonaceous domain. Fe,Ni, and Co may afford high yield of CNTs/CNFs within the carbonaceoussolid and containing some nitrogen, oxygen, and/or sulfur atoms from theincorporation of the heteroatoms into the CNT structure. Moreover, XPSexperiments have shown the presence of the heteroatoms within thecarbonaceous solids. Similar studies on crystalline calcined (oxygenpurification to remove the amorphous carbon, such as disclosed in U.S.Pat. Appl. Pub. No. 2008/0292530) samples show the presence of theheteroatoms. The choice of precursor materials (metal source andphthalonitrile) may allow varying the amount of heteroatoms and metalnanoparticles within the CNT and/or CNF-containing carbonaceous solids.

The following examples are given to illustrate specific applications.These specific examples are not intended to limit the scope of thedisclosure in this application. Specifics regarding any example may beapplicant to other or all embodiments.

EXAMPLE 1

Synthesis of a heteroaromatic phthalonitrile based on1,3-dihydroxypyrimidine and 4-nitrophthalonitrile—To a 100 mL,three-necked flask fitted with a thermometer, a Dean-Stark trap withcondenser, and a nitrogen inlet were added 1,3-dihydroxypyrimidine (5.00g, 44.6 mmol), 4-nitrophthalonitrile (15.83 g, 91.4 mmol), powderedanhydrous K₂CO₃ (13.0 g, 94.2 mmol), and N,N-dimethylformamide (DMF)(100 mL). The resulting mixture was heated at 80° C. for 6-8 h. Themixture was allowed to cool to ambient temperature and poured into a 5%aqueous HCl solution resulting in the precipitation of a solid. Thematerial was broken up and collected using a Buchner funnel. The whitesolid was washed with 200 mL of a 5% aqueous KOH solution, with 200 mLof distilled water until neutral, with 200 mL of a 5% aqueous HClsolution, and finally with 200 mL of water until neutral. The solventwas removed in vacuo and the solid was vacuum dried to yield theheteroaromatic phthalonitrile (14.4 g, 90% yield). IR [cm⁻¹]: δ 3058(C═CH), 2231 (C≡N), 1610 (C═N), 1589 (C═C), 1491 (aromatic), 1281 (CH₃),1248 (C—O), 1173 (C—O), 970 (C—O), 834 (aromatic).

EXAMPLE 2

Curing of a heteroaromatic phthalonitrile based on1,3-dihydroxypyrimidine and 4-nitrophthalonitrile with an aromaticamine—Samples containing the heteroaromatic phthalonitrile from Example1 and 2-3 weight % of bis(4-[4-aminophenoxy]phenyl)sulfone (p-BPAS) or1,3-bis(3-aminophenoxy)benzene (m-APB) were stirred at 250° C. for 2minutes and cured under nitrogen by heating at 270° C. for 12 h(overnight), 300° C. for 4 h, 350° C. for 4 h, and 375° C. for 8 h toafford a polymer. The polymers exhibited excellent thermal and oxidativestability up to 425° C. before any weight loss was detected.Catastrophic decomposition occurred after 450° C. in air.

A polymerization study of the phthalonitrile was achieved by DSCanalyses (FIG. 1) up to 400° C. in the presence of 5 weight % of p-BAPSto afford the corresponding thermoset. The monomer exhibited a meltingpoint at 261° C. and an exothermic transition peaking at about 270° C.attributed to the softening from the amorphous phase and to the reactionwith p-BAPS, respectively.

EXAMPLE 3

Synthesis of a heteroaromatic phthalonitrile based on 1,3-quinolinedioland 4-nitrophthalonitrile—To a 100 mL, three-necked flask fitted with athermometer, a Dean-Stark trap with condenser, and a nitrogen inlet wereadded 1,3-dihydroxypyrimidine (3.764 g, 23.3 mmol),4-nitrophthalonitrile (8.17 g, 47.2 mmol), powdered anhydrous K₂CO₃(10.00 g, 72.5 mmol), and N,N-dimethylformamide (DMF) (70 mL). Theresulting mixture was heated at 80° C. for 6-8 h. The mixture wasallowed to cool to ambient temperature and poured into a 5% aqueous HClsolution resulting in the precipitation of a solid. The material wasbroken up and collected using a Buchner funnel. The white solid waswashed with 200 mL of a 5% aqueous KOH solution, with 200 mL ofdistilled water until neutral, with 200 mL of a 5% aqueous HCl solution,and finally with 200 mL of water until neutral. The solvent was removedin vacuo and the solid was vacuum dried to yield the heteroaromaticphthalonitrile (8.88 g, 92% yield). IR [cm⁻¹]: δ 3060 (C═CH), 2232(C≡N), 1605 (C═N), 1589 (C═C), 1491 (aromatic), 1281 (CH₃), 1248 (C—O),1173 (C—O), 970 (C—O), 833 (aromatic).

EXAMPLE 4

Curing of a heteroaromatic phthalonitrile based on 1,3-quinolinediol and4-nitrophthalonitrile with an aromatic amine—Samples containing theheteroaromatic phthalonitrile from Example 3 and 2-3 weight % of p-BPASor m-APB were stirred at 250° C. for 2 minutes and cured under nitrogenby heating at 270° C. for 12 h (overnight), 300° C. for 4 h, 350° C. for4 h, and 375° C. for 8 h to afford a polymer. The polymers exhibitedexcellent thermal and oxidative stability up to 425° C. before anyweight loss was detected. Catastrophic decomposition occurred after 470°C. in air.

EXAMPLE 5

Synthesis of a heteroaromatic phthalonitrile based on2,6-dihydroxypyridine and 4-nitrophthalonitrile—To a 100 mL,three-necked flask fitted with a thermometer, a Dean-Stark trap withcondenser, and a nitrogen inlet were added 2,6-dihydroxypyridine (5.00g, 45.4 mmol), 4-nitrophthalonitrile (15.7 g, 91.0 mmol), powderedanhydrous K₂CO₃ (10.00 g, 72.5 mmol), and N,N-dimethylformamide (DMF)(100 mL). The resulting mixture was heated at 80° C. for 6-8 h. Themixture was allowed to cool to ambient temperature and poured into a 5%aqueous HCl solution resulting in the formation of a solid. The materialwas broken up and collected using a Buchner funnel. The white solid waswashed with 200 mL of a 5% aqueous KOH solution, with 200 mL ofdistilled water until neutral, with 200 mL of a 5% aqueous HCl solution,and finally with 200 mL of water until neutral. The solvent was removedin vacuo and the solid was vacuum dried to yield the heteroaromaticphthalonitrile (13.1 g, 80% yield). IR [cm⁻¹]: δ 3060 (C═CH), 2230 (CN),1605 (C═N), 1590 (C═C), 1491 (aromatic), 1281 (CH₃), 1248 (C—O), 1173(C—O), 970 (C—O), 832 (aromatic).

EXAMPLE 6

Curing of a heteroaromatic phthalonitrile based on 2,6-dihydroxypyridineand 4-nitrophthalonitrile with an aromatic amine—Samples containing theheteroaromatic phthalonitrile from Example 5 and 2-3 weight % of p-BPASor m-APB were stirred at 250° C. for 2 minutes and cured under nitrogenby heating at 270° C. for 12 h (overnight), 300° C. for 4 h, 350° C. for4 h, and 375° C. for 8 h to afford a polymer. The polymers exhibitedexcellent thermal and oxidative stability up to 425° C. before anyweight loss was detected. Catastrophic decomposition occurred after 470°C. in air.

EXAMPLE 7

Synthesis of a heteroaromatic phthalonitrile based on1,3-dihydroxythiophene and 4-nitrophthalonitrile—To a 100 mL,three-necked flask fitted with a thermometer, a Dean-Stark trap withcondenser, and a nitrogen inlet were added 1,3-dihydroxythiophene (5.00g, 43.1 mmol), 4-nitrophthalonitrile (14.9 g, 86.1 mmol), powderedanhydrous K₂CO₃ (14.8 g, 108 mmol), and N,N-dimethylformamide (DMF) (100mL). The resulting mixture was heated at 80° C. for 6-8 h. The mixturewas allowed to cool to ambient temperature and poured into a 5% aqueousHCl solution resulting in the precipitation of a solid. The material wasbroken up and collected using a Buchner funnel. The white solid waswashed with 200 mL of a 5% aqueous KOH solution, with 200 mL ofdistilled water until neutral, with 200 mL of a 5% aqueous HCl solution,and finally with 200 mL of water until neutral. The solvent was removedin vacuo and the solid was vacuum dried to yield the heteroaromaticphthalonitrile (13.5 g, 86% yield). IR [cm⁻¹]: δ 3060 (C═CH), 2230(C≡N), 1605 (C═N), 1590 (C═C), 1529 (S—C), 1491 (aromatic), 1410 (S—C),1281 (CH₃), 1248 (C—O), 1173 (C—O), 970 (C—O), 832 (aromatic).

EXAMPLE 8

Curing of a heteroaromatic phthalonitrile based on 1,3-dihydroxypyridineand 4-nitrophthalonitrile with an aromatic amine—Samples containing theheteroaromatic phthalonitrile from Example 7 and 2-3 weight % of p-BPASor m-APB were stirred at 250° C. for 2 minutes and cured under nitrogenby heating at 270° C. for 12 h (overnight), 300° C. for 4 h, 350° C. for4 h, and 375° C. for 8 h to afford a polymer. The polymers exhibitedexcellent thermal and oxidative stability up to 425° C. before anyweight loss was detected. Catastrophic decomposition occurred after 470°C. in air.

EXAMPLE 9

Formulation of carbon nanotubes with a heteroaromatic phthalonitrilebased on 1,3-dihydroxypyrimidine and 4-nitrophthalonitrile in asolvent—To a mixture of the heteroaromatic phthalonitrile from Example 1in an appropriate solvent was added various amounts of carbon nanotubes(0.01 to 20 weight %). The mixture was thoroughly mixed. The solvent wasremoved and the mixture was heated and degassed at 200° C. Then 3 weight% ofp-BPAS or m-APB was stirred in at 200° C. for 2 minutes and themixture was cured under nitrogen by heating at 270° C. for 12 h(overnight), 300° C. for 4 h, 350° C. for 4 h, and 375° C. for 8 h toafford a polymer. The polymeric compositions exhibited excellent thermaland oxidative stability up to 425-450° C. before any weight loss wasdetected. Catastrophic decomposition occurred after 500° C. in air.

EXAMPLE 10

Formulation of clay with a heteroaromatic phthalonitrile based on1,3-dihydroxypyrimidine and 4-nitrophthalonitrile in a solvent—To amixture of the heteroaromatic phthalonitrile from Example 1 in anappropriate solvent was added various amount of clay (hydrated aluminumsilicate, 0.01 to 20 weight %). The resulting mixtures were thoroughlymixed. The solvent was removed and the mixture was heated and degassedat 200° C. Then 3-4 weight % of p-BPAS or m-APB was stirred in at 200°C. for 2 minutes and the mixture was cured under nitrogen by heating at270° C. for 12 h (overnight), 300° C. for 4 h, 350° C. for 4 h, and 375°C. for 8 h to afford a polymer. The polymeric mixtures or compositionsexhibited excellent thermal and oxidative stability up to 450° C. beforeany weight loss was detected. Catastrophic decomposition occurred after490° C. in air.

EXAMPLE 11

Formulation of carbon nanofibers with a heteroaromatic phthalonitrilebased on 1,3-dihydroxypyrimidine and 4-nitrophthalonitrile in asolvent—To a mixture of the heteroaromatic phthalonitrile from Example 1in an appropriate solvent was added various amounts of carbon nanofibers(0.01 to 20 weight %). The mixtures were thoroughly mixed by stirring.The solvent was removed and the mixture was heated and degassed at 200°C. Then 4 weight % ofp-BPAS or m-APB was stirred in at 200° C. for 2minutes and the mixture was cured under nitrogen by heating at 270° C.for 12 h (overnight), 300° C. for 4 h, 350° C. for 4 h, and 375° C. for8 h to afford a polymer. The polymeric mixtures or compositionsexhibited excellent thermal and oxidative stability up to 425-450° C.before any weight loss was detected. Catastrophic decomposition occurredafter 500° C. in air.

Example 12

Formulation of a metal oxide with heteroaromatic phthalonitrile based on1,3-dihydroxypyrimidine and 4-nitrophthalonitrile n a solvent—To amixture of the heteroaromatic phthalonitrile from Example 1 in anappropriate solvent was added various amount of powdered zinc oxide(0.01 to 20 weight %) with thorough mixing. The solvent was removed andthe mixture was heated and degassed at 200° C. Then 4-5 weight % ofp-BPAS or m-APB was stirred in at 200° C. for 2 minutes and the mixturecured under nitrogen by heating at 270° C. for 12 h (overnight), 300° C.for 4 h, 350° C. for 4 h, and 375° C. for 8 h to afford a polymer. Thepolymeric mixtures or compositions exhibited excellent thermal andoxidative stability up to 450° C. before a weight loss was detected.Catastrophic decomposition occurred after 500° C. in air.

EXAMPLE 13

Formulation of clay with a heteroaromatic phthalonitrile based on1,3-dihydroxypyrimidine and 4-nitrophthalonitrile by physical mixing—Tothe heteroaromatic phthalonitrile from Example 1 was added variousamounts of clay (hydrated aluminum silicate; 0.01 to 20 weight %).Thorough mixing was followed by degassing at 200° C. Then 3-5 weight %of p-BPAS or m-APB was stirred in at 200° C. for 2 minutes and themixture was cured under nitrogen by heating at 270° C. for 12 h(overnight), 300° C. for 4 h, 350° C. for 4 h, and 375° C. for 8 h toafford a polymer. The polymeric mixtures or compositions exhibitedexcellent thermal and oxidative stability up to 445° C. before a weightloss was detected. Catastrophic decomposition occurred after 500° C. inair.

EXAMPLE 14

Formulation of boric acid with a heteroaromatic phthalonitrile based on1,3-dihydroxypyrimidine and 4-nitrophthalonitrile by physical mixing—Tothe heteroaromatic phthalonitrile from Example 1 was added variousamount of boric acid (0.01 to 40 weight %). Thorough mixing was followedby almost immediate curing. The mixture was further cured under nitrogenby heating at 270° C. for 12 h (overnight), 300° C. for 4 h, 350° C. for4 h, and 375° C. for 8 h to afford a polymer. The polymeric mixtures orcompositions exhibited excellent thermal and oxidative stability up to460° C. before a weight loss was detected. Catastrophic decompositionoccurred after 500° C. in air.

EXAMPLE 15

Synthesis of 2:1 oligomeric heteroaromatic phthalonitrile based on1,3-dihydroxypyrimidine and 1,4-dibromobenzene—To a 100 mL, three-neckedflask fitted with a thermometer, a Dean-Stark trap with condenser, and anitrogen inlet were added 1,3-dihydroxypyrimidine (5.00 g, 44.6 mmol),1,4-dibromobenzene (5.21 g, 22.1 mmol), (PPh₃)₃CuBr (0.2 g), powderedanhydrous K₂CO₃ (12.3 g, 89.1 mmol), toluene (10 mL), andN,N-dimethylformamide (DMF) (75 mL). The resulting mixture was degassedwith argon at ambient temperature and the Dean-Stark trap was filledwith toluene. The mixture was refluxed at 135-145° C. under an argonatmosphere for 12 to 18 h or until no more water was observed beingcollected in the Dean-Stark trap. FTIR spectroscopy was used to confirmand to monitor the formation of the desired oligomeric product. Toluenewas then removed by distillation and the reaction mixture was cooled to50° C. At this time, 4-nitrophthalonitrile (7.78 g, 44.9 mmol) was addedin one portion and the reaction mixture was heated at 80° C. for 6-8 h.The mixture was allowed to cool to ambient temperature and poured into a5% aqueous HCl solution resulting in the precipitation of a solid. Thematerial was broken up and collected using a Buchner funnel. The whitesolid was dissolved in chloroform (200 mL), and washed with 200 mL of a5% aqueous KOH solution, with 200 mL of distilled water until neutral,with 200 mL of a 5% aqueous HCl solution, and finally with 200 mL ofwater until neutral. The solvent was removed in vacuo and the solid wasvacuum dried to yield the 2:1 oligomeric heteroaromatic phthalonitrile(11.00 g, 91% yield). IR [cm⁻¹]: δ 3075 (C═CH), 2232 (C≡N), 1600 (C═N),1585 (C═C), 1477 (aromatic), 1308 (aromatic), 1244 (C—O), 1172 (C—O),975 (C—O), 837 (aromatic).

EXAMPLE 16

Curing of 2:1 oligomeric heteroaromatic phthalonitrile based on1,3-dihydroxypyrimidine and 1,4-dibromobenzene with an aromaticamine—Samples containing the 2:1 oligomeric heteroaromaticphthalonitrile from Example 15 and 2-3 weight % of p-BPAS or m-APB werestirred at 200° C. for 2 minutes and cured under nitrogen by heating at270° C. for 12 h (overnight), 300° C. for 4 h, 350° C. for 4 h, and 375°C. for 8 h to afford a polymer. The polymers exhibited excellent thermaland oxidative stability up to 450° C. before any weight loss wasdetected. Catastrophic decomposition occurred after 500° C.

EXAMPLE 17

Synthesis of 3:2 oligomeric heteroaromatic phthalonitrile based on1,3-dihydroxypyrimidine and 1,3-dibromobenzene—To a 100 mL, three-neckedflask fitted with a thermometer, a Dean-Stark trap with condenser, and anitrogen inlet were added 1,3-dihydroxypyrimidine (5.00 g, 44.6 mmol),1,3-dibromobenzene (7.02 g, 29.7 mmol), (PPh₃)₃CuBr (0.2 g), powderedanhydrous K₂CO₃ (12.3 g, 89.1 mmol), toluene (10 mL), andN,N-dimethylformamide (DMF) (75 mL). The resulting mixture was degassedwith argon at ambient temperature and the Dean-Stark trap was filledwith toluene. The mixture was refluxed at 135-145° C. under an argonatmosphere for 12 to 18 h or until no more water was observed beingcollected in the Dean-Stark trap. FTIR spectroscopy was used to confirmand to monitor the formation of the desired oligomeric product. Toluenewas then removed by distillation and the reaction mixture was cooled to50° C. At this time, 4-nitrophthalonitrile (5.32 g, 30.2 mmol) was addedin one portion and the reaction mixture was heated at 80° C. for 6-8 h.The mixture was allowed to cool to ambient temperature and poured into a5% aqueous HCl solution resulting in the precipitation of a solid. Thematerial was broken up and collected using a Buchner funnel. The whitesolid was dissolved in chloroform (200 mL), and washed with 200 mL of a5% aqueous KOH solution, with 200 mL of distilled water until neutral,with 200 mL of a 5% aqueous HCl solution, and finally with 200 mL ofwater until neutral. The solvent was removed in vacuo and the solid wasvacuum dried to yield the 3:2 oligomeric heteroaromatic phthalonitrile(8.89 g, 80% yield). IR [cm⁻¹]: δ 3075 (C═CH), 2232 (C≡N), 1600 (C═N),1585 (C═C), 1477 (aromatic), 1308 (aromatic), 1244 (C—O), 1172 (C—O),975 (C—O), 837 (aromatic).

EXAMPLE 18

Curing of 3:2 oligomeric heteroaromatic phthalonitrile based on1,3-dihydroxypyrimidine and 1,3-dibromobenzene with an aromaticamine—Samples containing the 3:2 oligomeric heteroaromaticphthalonitrile from Example 17 and 2-3 weight % of p-BPAS or m-APB werestirred at 200° C. for 2 minutes and cured under nitrogen by heating at270° C. for 12 h (overnight), 300° C. for 4 h, 350° C. for 4 h, and 375°C. for 8 h to afford a polymer. The polymers exhibited excellent thermaland oxidative stability up to 450° C. before any weight loss wasdetected. Catastrophic decomposition occurred after 500° C.

EXAMPLE 19

Synthesis of 2:1 oligomeric heteroaromatic phthalonitrile based onbisphenol A and 2,5-dibromothiophene—To a 100 mL, three-necked flaskfitted with a thermometer, a Dean-Stark trap with condenser, and anitrogen inlet were added bisphenol A (5.00 g, 22.0 mmol),2,5-dibromothiophene (2.62 g, 10.8 mmol), (PPh₃)₃CuBr (0.2 g), powderedanhydrous K₂CO₃ (6.00 g, 43.5 mmol), toluene (10 mL), andN,N-dimethylformamide (DMF) (70 mL). The resulting mixture was degassedwith argon at ambient temperature and the Dean-Stark trap was filledwith toluene. The mixture was refluxed at 135-145° C. under an argonatmosphere for 12 to 18 h or until no more water was observed beingcollected in the Dean-Stark trap. FTIR spectroscopy was used to confirmand to monitor the formation of the desired oligomeric product. Toluenewas then removed by distillation and the reaction mixture was cooled to50° C. At this time, 4-nitrophthalonitrile (3.82 g, 22.1 mmol) was addedin one portion and the reaction mixture was heated at 80° C. for 6-8 h.The mixture was allowed to cool to ambient temperature and poured into a5% aqueous HCl solution resulting in the precipitation of a solid. Thematerial was broken up and collected using a Buchner funnel. The whitesolid was dissolved in chloroform (200 mL), and washed with 200 mL of a5% aqueous KOH solution, with 200 mL of distilled water until neutral,with 200 mL of a 5% aqueous HCl solution, and finally with 200 mL ofwater until neutral. The solvent was removed in vacuo and the solid wasvacuum dried to yield the 2:1 oligomeric heteroaromatic phthalonitrile(6.32 g, 73% yield). IR [cm⁻¹]: δ 3075 (C═CH), 2969 (CH₃), 2232 (C≡N),1585 (C═C), 1530 (S—C), 1477 (aromatic), 1410 (S—C), 1308 (aromatic),1244 (C—O), 1172 (C—O), 975 (C—O), 837 (aromatic).

EXAMPLE 20

Curing of 2:1 oligomeric heteroaromatic phthalonitrile based onbisphenol A and 2,5-dibromothiophene with an aromatic amine—Samplescontaining the 2:1 oligomeric heteroaromatic phthalonitrile from Example19 and 2-3 weight % of p-BPAS or m-APB were stirred at 200° C. for 2minutes and cured under nitrogen by heating at 270° C. for 12 h(overnight), 300° C. for 4 h, 350° C. for 4 h, and 375° C. for 8 h toafford a polymer. The polymers exhibited excellent thermal and oxidativestability up to 425° C. before any weight loss was detected.Catastrophic decomposition occurred after 475° C.

A polymerization study of the phthalonitrile was achieved by DSCanalyses (FIG. 2) up to 400° C. in the presence of 5 weight % of p-BAPSto afford the corresponding thermoset. Endothermic and exothermictransitions appeared at 80 and 300° C., respectively, attributed to theglass transition temperature (T_(g)) and the polymerization reaction.The phthalonitrile exhibited a low softening temperature, was completelyfree flowing around 150° C. (as determined by a visual melting test) andhad a long processing window (˜100° C.) before reaction with the curingadditive occurred to afford the thermoset.

EXAMPLE 21

Synthesis of 2:1 oligomeric heteroaromatic phthalonitrile based onresorcinol and 2,5-dibromothiophene—To a 100 mL, three-necked flaskfitted with a thermometer, a Dean-Stark trap with condenser, and anitrogen inlet were added resorcinol (5.00 g, 45.4 mmol),2,5-dibromothiophene (5.49 g, 22.7 mmol), (PPh₃)₃CuBr (0.2 g), powderedanhydrous K₂CO₃ (8.22 g, 113 mmol), toluene (25 mL), andN,N-dimethylformamide (DMF) (100 mL). The resulting mixture was degassedwith argon at ambient temperature and the Dean-Stark trap was filledwith toluene. The mixture was refluxed at 135-145° C. under an argonatmosphere for 12 to 18 h or until no more water was observed beingcollected in the Dean-Stark trap. FTIR spectroscopy was used to confirmand to monitor the formation of the desired oligomeric product. Toluenewas then removed by distillation and the reaction mixture was cooled to50° C. At this time, 4-nitrophthalonitrile (3.90 g, 22.5 mmol) was addedin one portion and the reaction mixture was heated at 80° C. for 6-8 h.The mixture was allowed to cool to ambient temperature and poured into a5% aqueous HCl solution resulting in the precipitation of a solid. Thematerial was broken up and collected using a Buchner funnel. The whitesolid was dissolved in chloroform (200 mL), and washed with 200 mL of a5% aqueous KOH solution, with 200 mL of distilled water until neutral,with 200 mL of a 5% aqueous HCl solution, and finally with 200 mL ofwater until neutral. The solvent was removed in vacuo and the solid wasvacuum dried to yield the 2:1 oligomeric heteroaromatic phthalonitrile(8.81 g, 85% yield). IR [cm⁻¹]: δ 3075 (C═CH), 2232 (C≡N), 1585 (C═C),1530 (S—C), 1477 (aromatic), 1410 (S—C), 1308 (aromatic), 1244 (C—O),1172 (C—O), 975 (C—O), 837 (aromatic).

EXAMPLE 22

Curing of 2:1 oligomeric heteroaromatic phthalonitrile based onresorcinol and 2,5-dibromothiophene with an aromatic amine—Samplescontaining the 2:1 oligomeric heteroaromatic phthalonitrile from Example21 and 2-3 weight % of p-BPAS or m-APB were stirred at 200° C. for 2minutes and cured under nitrogen by heating at 270° C. for 12 h(overnight), 300° C. for 4 h, 350° C. for 4 h, and 375° C. for 8 h toafford a polymer. The polymers exhibited excellent thermal and oxidativestability up to 425° C. before any weight loss was detected.Catastrophic decomposition occurred after 475° C.

EXAMPLE 23

Synthesis of 2:1 oligomeric heteroaromatic phthalonitrile based on2,5-dihydroxythiophene and 1,3-dibromobenzene—To a 100 mL, three-neckedflask fitted with a thermometer, a Dean-Stark trap with condenser, and anitrogen inlet were added 2,5-dihydroxythiophene (5.00 g, 43.1 mmol),1,3-dibromobenzene (5.03 g, 21.3 mmol), (PPh₃)₃CuBr (0.2 g), powderedanhydrous K₂CO₃ (14.8 g, 108 mmol), toluene (25 mL), andN,N-dimethylformamide (DMF) (100 mL). The resulting mixture was degassedwith argon at ambient temperature and the Dean-Stark trap was filledwith toluene. The mixture was refluxed at 135-145° C. under an argonatmosphere for 12 to 18 h or until no more water was observed beingcollected in the Dean-Stark trap. FTIR spectroscopy was used to confirmand to monitor the formation of the desired oligomeric product. Toluenewas then removed by distillation and the reaction mixture was cooled to50° C. At this time, 4-nitrophthalonitrile (13.1 g, 75.6 mmol) was addedin one portion and the reaction mixture was heated at 80° C. for 6-8 h.The mixture was allowed to cool to ambient temperature and poured into a5% aqueous HCl solution resulting in the precipitation of a solid. Thematerial was broken up and collected using a Buchner funnel. The whitesolid was dissolved in chloroform (200 mL), and washed with 200 mL of a5% aqueous KOH solution, with 200 mL of distilled water until neutral,with 200 mL of a 5% aqueous HCl solution, and finally with 200 mL ofwater until neutral. The solvent was removed in vacuo and the solid wasvacuum dried to yield the 2:1 oligomeric heteroaromatic phthalonitrile(9.40 g, 90% yield). IR [cm⁻¹]: δ 3075 (C═CH), 2232 (C≡N), 1585 (C═C),1530 (S—C), 1477 (aromatic), 1410 (S—C), 1308 (aromatic), 1244 (C—O),1172 (C—O), 975 (C—O), 837 (aromatic).

EXAMPLE 24

Curing of 2:1 oligomeric heteroaromatic phthalonitrile based on2,5-dihydroxythiophene and 1,3-dibromobenzene with an aromaticamine—Samples containing the 2:1 oligomeric heteroaromaticphthalonitrile from Example 23 and 2-3 weight % of p-BPAS or m-APB werestirred at 200° C. for 2 minutes and cured under nitrogen by heating at270° C. for 12 h (overnight), 300° C. for 4 h, 350° C. for 4 h, and 375°C. for 8 h to afford a polymer. The polymers exhibited excellent thermaland oxidative stability up to 425° C. before any weight loss wasdetected. Catastrophic decomposition occurred after 475° C.

EXAMPLE 25

Synthesis of 2:1 oligomeric heteroaromatic phthalonitrile based on2,6-dihydroxypyridine and 2,5-dibromothiophene—To a 100 mL, three-neckedflask fitted with a thermometer, a Dean-Stark trap with condenser, and anitrogen inlet were added 2,6-dihydroxypyridine (5.00 g, 45.0 mmol),2,5-dibromothiophene (5.46 g, 90.9 mmol), (PPh₃)₃CuBr (0.2 g), powderedanhydrous K₂CO₃ (15.5 g, 113 mmol), toluene (30 mL), andN,N-dimethylformamide (DMF) (120 mL). The resulting mixture was degassedwith argon at ambient temperature and the Dean-Stark trap was filledwith toluene. The mixture was refluxed at 135-145° C. under an argonatmosphere for 12 to 18 h or until no more water was observed beingcollected in the Dean-Stark trap. FTIR spectroscopy was used to confirmand to monitor the formation of the desired oligomeric product. Toluenewas then removed by distillation and the reaction mixture was cooled to50° C. At this time, 4-nitrophthalonitrile (7.87 g, 45.4 mmol) was addedin one portion and the reaction mixture was heated at 80° C. for 6-8 h.The mixture was allowed to cool to ambient temperature and poured into a5% aqueous HCl solution resulting in the precipitation of a solid. Thematerial was broken up and collected using a Buchner funnel. The whitesolid was dissolved in chloroform (200 mL), and washed with 200 mL of a5% aqueous KOH solution, with 200 mL of distilled water until neutral,with 200 mL of a 5% aqueous HCl solution, and finally with 200 mL ofwater until neutral. The solvent was removed in vacuo and the solid wasvacuum dried to yield the 2:1 oligomeric heteroaromatic phthalonitrile(12.44 g, 80% yield). IR [cm⁻¹]: δ 3075 (C═CH), 2232 (C≡N), 1600 (C═N),1585 (C═C), 1530 (S—C), 1477 (aromatic), 1410 (S—C), 1308 (aromatic),1244 (C—O), 1172 (C—O), 975 (C—O), 837 (aromatic).

EXAMPLE 26

Curing of 2:1 oligomeric heteroaromatic phthalonitrile based on2,6-dihydroxypyridine and 2,5-dibromothiophene with an aromaticamine—Samples containing the 2:1 oligomeric heteroaromaticphthalonitrile from Example 25 and 2-3 weight % of p-BPAS or m-APB werestirred at 200° C. for 2 minutes and cured under nitrogen by heating at270° C. for 12 h (overnight), 300° C. for 4 h, 350° C. for 4 h, and 375°C. for 8 h to afford a polymer. The polymers exhibited excellent thermaland oxidative stability up to 450° C. before any weight loss wasdetected. Catastrophic decomposition occurred after 495° C.

EXAMPLE 27

Synthesis of 2:1 oligomeric heteroaromatic phthalonitrile based on2,6-dihydroxypyridine and 1,3-dibromobenzene—To a 100 mL, three-neckedflask fitted with a thermometer, a Dean-Stark trap with condenser, and anitrogen inlet were added 2,6-dihydroxypyridine (5.00 g, 45.0 mmol),1,3-dibromobenzene (5.31 g, 22.5 mmol), (PPh₃)₃CuBr (0.2 g), powderedanhydrous K₂CO₃ (15.5 g, 113 mmol), toluene (10 mL), andN,N-dimethylformamide (DMF) (50 mL). The resulting mixture was degassedwith argon at ambient temperature and the Dean-Stark trap was filledwith toluene. The mixture was refluxed at 135-145° C. under an argonatmosphere for 12 to 18 h or until no more water was observed beingcollected in the Dean-Stark trap. FTIR spectroscopy was used to confirmand to monitor the formation of the desired oligomeric product. Toluenewas then removed by distillation and the reaction mixture was cooled to50° C. At this time, 4-nitrophthalonitrile (7.55 g, 43.6 mmol) was addedin one portion and the reaction mixture was heated at 80° C. for 6-8 h.The mixture was allowed to cool to ambient temperature and poured into a5% aqueous HCl solution resulting in the precipitation of a solid. Thematerial was broken up and collected using a Buchner funnel. The whitesolid was dissolved in chloroform (200 mL), and washed with 200 mL of a5% aqueous KOH solution, with 200 mL of distilled water until neutral,with 200 mL of a 5% aqueous HCl solution, and finally with 200 mL ofwater until neutral. The solvent was removed in vacuo and the solid wasvacuum dried to yield the 2:1 oligomeric heteroaromatic phthalonitrile(10.7 g, 90% yield). IR [cm⁻¹]: δ 3075 (C═CH), 2232 (C≡N), 1603 (C═N),1585 (C═C), 1477 (aromatic), 1310 (aromatic), 1244 (C—O), 1172 (C—O),975 (C—O), 835 (aromatic).

EXAMPLE 28

Curing of 2:1 oligomeric heteroaromatic phthalonitrile based on2,6-dihydroxypyridine and 1,3-dibromobenzene with an aromaticamine—Samples containing the 2:1 oligomeric heteroaromaticphthalonitrile from Example 27 and 2-3 weight % of p-BPAS or m-APB werestirred at 200° C. for 2 minutes and cured under nitrogen by heating at270° C. for 12 h (overnight), 300° C. for 4 h, 350° C. for 4 h, and 375°C. for 8 h to afford a polymer. The polymers exhibited excellent thermaland oxidative stability up to 450° C. before any weight loss wasdetected. Catastrophic decomposition occurred after 500° C.

EXAMPLE 29

Formulation of carbon nanotubes with a 2:1 oligomeric heteroaromaticphthalonitrile based on 1,3-dihydroxypyrimidine and 1,4-dibromobenzenein a solvent—To a mixture of the 2:1 oligomeric heteroaromaticphthalonitrile from Example 15 in an appropriate solvent was addedvarious amounts of carbon nanotubes (0.01 to 20 weight %). The mixturewas thoroughly mixed. The solvent was removed and the mixture was heatedand degassed at 200° C. Then 3 weight % of p-BPAS or m-APB was stirredin at 200° C. for 2 minutes and the mixture was cured under nitrogen byheating at 270° C. for 12 h (overnight), 300° C. for 4 h, 350° C. for 4h, and 375° C. for 8 h to afford a polymer. The polymeric compositionsexhibited excellent thermal and oxidative stability up to 425-450° C.before any weight loss was detected. Catastrophic decomposition occurredafter 500° C. in air.

Example 30

Formulation of clay with a 2:1 oligomeric heteroaromatic phthalonitrilebased on 1,3-dihydroxypyrimidine and 1,4-dibromobenzene in a solvent—Toa mixture of the 2:1 oligomeric heteroaromatic phthalonitrile fromExample 15 in an appropriate solvent was added various amount of clay(hydrated aluminum silicate; 0.01 to 20 weight %). The resultingmixtures were thoroughly mixed. The solvent was removed and the mixturewas heated and degassed at 200° C. Then 3-4 weight % of p-BPAS or m-APBwas stirred in at 200° C. for 2 minutes and the mixture was cured undernitrogen by heating at 270° C. for 12 h (overnight), 300° C. for 4 h,350° C. for 4 h, and 375° C. for 8 h to afford a polymer. The polymericmixtures or compositions exhibited excellent thermal and oxidativestability up to 430-460° C. before any weight loss was detected.Catastrophic decomposition occurred after 500° C. in air.

EXAMPLE 31

Formulation of carbon nanofibers with a 2:1 oligomeric heteroaromaticphthalonitrile based on 1,3-dihydroxypyrimidine and 1,4-dibromobenzenein a solvent—To a mixture of the 2:1 oligomeric heteroaromaticphthalonitrile from Example 15 in an appropriate solvent was addedvarious amounts of carbon nanofibers (0.01 to 20 weight %). The mixtureswere thoroughly mixed by stirring. The solvent was removed and themixture heated and degassed at 200° C. Then 4 weight % of p-BPAS orm-APB was stirred in at 200° C. for 2 minutes and the mixture was curedunder nitrogen by heating at 270° C. for 12 h (overnight), 300° C. for 4h, 350° C. for 4 h, and 375° C. for 8 h to afford a polymer. Thepolymeric mixtures or compositions exhibited excellent thermal andoxidative stability up to 425-450° C. before any weight loss wasdetected. Catastrophic decomposition occurred after 500° C. in air.

EXAMPLE 32

Formulation of a metal oxide with 2:1 oligomeric heteroaromaticphthalonitrile based on 1,3-dihydroxypyrimidine and 1,4-dibromobenzenein a solvent—To a mixture of the 2:1 oligomeric heteroaromaticphthalonitrile from Example 15 in an appropriate solvent was addedvarious amount of powdered zinc oxide (0.01 to 20 weight %) withthorough mixing. The solvent was removed and the mixture was heated anddegassed at 200° C. Then 4-5 weight % of p-BPAS or m-APB was stirred inat 200° C. for 2 minutes and the mixture was cured under nitrogen byheating at 270° C. for 12 h (overnight), 300° C. for 4 h, 350° C. for 4h, and 375° C. for 8 h to afford a polymer. The polymeric mixtures orcompositions exhibited excellent thermal and oxidative stability up to450° C. before a weight loss was detected. Catastrophic decompositionoccurred after 500° C. in air.

EXAMPLE 33

Formulation of clay with a 2:1 oligomeric heteroaromatic phthalonitrilebased on 1,3-dihydroxypyrimidine and 1,4-dibromobenzene by physicalmixing—To the 2:1 oligomeric heteroaromatic phthalonitrile from Example15 was added various amount of clay (hydrated aluminum silicate; 0.01 to20 weight %). Thorough physical mixing was followed by degassed at 200°C. Then 3-5 weight % ofp-BPAS or m-APB was stirred in at 200° C. for 2minutes and the mixture was cured under nitrogen by heating at 270° C.for 12 h (overnight), 300° C. for 4 h, 350° C. for 4 h, and 375° C. for8 h to afford a polymer. The polymeric mixtures or compositionsexhibited excellent thermal and oxidative stability up to 450° C. beforea weight loss was detected. Catastrophic decomposition occurred after500° C. in air.

EXAMPLE 34

Formulation of boric acid with a 2:1 oligomeric heteroaromaticphthalonitrile based on 1,3-dihydroxypyrimidine and 1,4-dibromobenzeneby physical mixing—To the 2:1 oligomeric heteroaromatic phthalonitrilefrom Example 15 was added various amount of boric acid (0.01 to 40weight %). Thorough mixing was followed by almost immediate curing. Themixture was further cured under nitrogen by heating at 270° C. for 12 h(overnight), 300° C. for 4 h, 350° C. for 4 h, and 375° C. for 8 h toafford a polymer. The polymeric mixtures or compositions exhibitedexcellent thermal and oxidative stability up to 460° C. before a weightloss was detected. Catastrophic decomposition occurred after 500° C. inair.

EXAMPLE 35

Synthesis of 1/20 molar mixture of octacarbonyldicobalt and aheteroaromatic phthalonitrile based on 1,3-dihydroxypyrimidine and4-nitrophthalonitrile—Co₂(CO)₈ (47 mg, 0.137 mmol), heteroaromaticphthalonitrile (1.00 g, 2.74 mmol) and 10 ml of methylene chloride wereadded to a 50 ml round bottomed flask. The homogeneous mixture wasallowed to stir for 1 h before the solvent was removed under reducedpressure. The mixture was vacuum dried to yield a dark solid.

EXAMPLE 36

Thermal conversion of 1/20 molar mixture of octacarbonyldicobalt and aheteroaromatic phthalonitrile based on 1,3-dihydroxypyrimidine and4-nitrophthalonitrile to carbon nanotube-cobalt nanoparticlecomposition—The mixture from Example 35 (25 mg) was heated in a TGAchamber under nitrogen at 10° C./min to 1000° C. resulting in a shapedcomposition and a char yield of 80%. X-ray studies confirm the presenceof carbon nanotubes-cobalt nanoparticles in the carbon composition. Thex-ray diffraction study showed the four characteristic reflections[(002), (100), (004), and (110)] values for crystalline carbon nanotubesand the pattern for cobalt nanoparticles.

X-ray analysis (FIG. 3) shows the presence of carbon nanotubes in thedeveloping carbonaceous system when heated to 1000° C. with thecharacteristic graphite (002) peak (CNT) appearing around 25.9. Only atrace amount of transition metal (Co, Ni, and Fe) appeared to be neededto ensure the formation of CNTs. As the temperature of the carbonaceoussystem was increased, higher concentrations and yields of CNTs wereformed.

EXAMPLE 37

Synthesis of 1/40 molar mixture of octacarbonyldicobalt and aheteroaromatic phthalonitrile based on 1,3-dihydroxypyrimidine and4-nitrophthalonitrile—Co₂(CO)₈ (23 mg, 0.069 mmol), heteroaromaticphthalonitrile (1.00 g, 2.74 mmol) and 10 ml of methylene chloride wereadded to a 50 ml round bottomed flask. The homogeneous mixture wasallowed to stir for 1 h before the solvent was removed under reducedpressure. The mixture was vacuum dried to yield a dark solid.

EXAMPLE 38

Thermal conversion of 1/40 molar mixture of octacarbonyldicobalt and aheteroaromatic phthalonitrile based on 1,3-dihydroxypyrimidine and4-nitrophthalonitrile to carbon nanotube-cobalt nanoparticlecomposition—The mixture from Example 37 (50 mg) was heated in a TGAchamber under nitrogen at 10° C./min to 1000° C. resulting in a shapedcomposition and a char yield of 80%. X-ray studies confirm the presenceof carbon nanotubes-cobalt nanoparticles in the carbon composition. Thex-ray diffraction study showed the four characteristic reflections[(002), (100), (004), and (110)] values for crystalline carbon and thepattern for cobalt nanoparticles

EXAMPLE 39

Synthesis of 1/10 molar mixture of octacarbonyldicobalt and aheteroaromatic phthalonitrile based on 1,3-dihydroxypyrimidine and4-nitrophthalonitrile—Co₂(CO)₈ (94 mg, 0.274 mmol), heteroaromaticphthalonitrile (1.00 g, 2.74 mmol) and 10 ml of methylene chloride wereadded to a 50 ml round bottomed flask. The homogeneous mixture wasallowed to stir for 1 h before the solvent was removed under reducedpressure. The mixture was vacuum dried to yield a dark solid.

EXAMPLE 40

Thermal conversion of 1/10 molar mixture of octacarbonyldicobalt and aheteroaromatic phthalonitrile based on 1,3-dihydroxypyrimidine and4-nitrophthalonitrile to carbon nanotube-cobalt nanoparticlecomposition—The mixture from Example 39 (50 mg) was heated in a TGAchamber under nitrogen at 10° C./min to 1000° C. resulting in a shapedcomposition and a char yield of 75%. X-ray studies confirm the presenceof carbon nanotubes-cobalt nanoparticles in the carbon composition. Thex-ray diffraction study showed the four characteristic reflections[(002), (100), (004), and (110)] values for crystalline carbon nanotubesand the pattern for cobalt nanoparticles

EXAMPLE 41

Synthesis of 1/20 molar mixture of iron carbonyl and a heteroaromaticphthalonitrile based on 1,3-quinolinediol and4-nitrophthalonitrile—Fe₂(CO)₉ (44 mg, 0.121 mmol), heteroaromaticphthalonitrile (1.00 g, 2.42 mmol) and 10 ml of chloroform were added toa 50 ml round bottomed flask. The homogeneous mixture was allowed tostir for 1 h before the solvent was removed under reduced pressure. Themixture was vacuum dried to yield a dark solid.

EXAMPLE 42

Thermal conversion of 1/20 molar mixture of iron carbonyl and aheteroaromatic phthalonitrile based on 1,3-quinolinediol and4-nitrophthalonitrile to carbon nanotube-cobalt nanoparticlecomposition—The mixture from Example 41 (47 mg) was heated in a TGAchamber under nitrogen at 10° C./min to 1000° C. resulting in a shapedcomposition and a char yield of 81%. X-ray studies confirm the presenceof carbon nanotubes-iron nanoparticles in the carbon composition. Thex-ray diffraction study showed the four characteristic reflections[(002), (100), (004), and (110)] values for crystalline carbon nanotubesand the pattern for cobalt nanoparticles

EXAMPLE 43

Synthesis of 1/10 molar mixture of nickel cyclooctadiene and aheteroaromatic phthalonitrile based on 1,3-quinolinediol and4-nitrophthalonitrile—Nickel cyclooctadiene (67 mg, 0.242 mmol),heteroaromatic phthalonitrile (1.00 g, 2.42 mmol) and 10 ml of methylenechloride were added to a 50 ml round bottomed flask. The homogeneousmixture was allowed to stir for 2 h before the solvent was removed underreduced pressure. The mixture was vacuum dried to yield a dark solid.

EXAMPLE 44

Thermal conversion of 1/10 molar mixture of nickel cyclooctadiene and aheteroaromatic phthalonitrile based on 1,3-quinolinediol and4-nitrophthalonitrile to carbon nanotube-cobalt nanoparticlecomposition—The mixture from Example 43 (22 mg) was heated in a TGAchamber under nitrogen at 10° C./min to 1000° C. resulting in a shapedcomposition and a char yield of 78%. X-ray studies confirm the presenceof carbon nanotubes-nickel nanoparticles in the carbon composition. Thex-ray diffraction study showed the four characteristic reflections[(002), (100), (004), and (110)] values for crystalline carbon nanotubesand the pattern for nickel nanoparticles

EXAMPLE 45

Synthesis of 1/20 molar mixture of octacarbonyldicobalt, copperacetylacetonate and a heteroaromatic phthalonitrile based on1,3-quinolinediol and 4-nitrophthalonitrile—Co₂(CO)₈ (44 mg, 0.121mmol), Cu acetylacetonate (32 mg, 0.121 mmol), heteroaromaticphthalonitrile (1.00 g, 2.42 mmol) and 10 ml of chloroform were added toa 50 ml round bottomed flask. The homogeneous mixture was allowed tostir for 1 h before the solvent was removed under reduced pressure. Themixture was vacuum dried to yield a dark solid.

EXAMPLE 46

Thermal conversion of 1/20 molar mixture of octacarbonyldicobalt, copperacetylacetonate and a heteroaromatic phthalonitrile based on1,3-quinolinediol and 4-nitrophthalonitrile to carbon nanotube-cobaltnanoparticle composition—The mixture from Example 45 (55 mg) was heatedin a TGA chamber under nitrogen at 10° C./min to 1000° C. resulting in ashaped composition and a char yield of 73%. X-ray studies confirm thepresence of carbon nanotubes-cobalt-copper nanoparticles in the carboncomposition. The x-ray diffraction study showed the four characteristicreflections [(002), (100), (004), and (110)] values for crystallinecarbon nanotubes and the pattern for cobalt and copper nanoparticles

EXAMPLE 47

Synthesis of 1/20 molar mixture of octacarbonyldicobalt, copperacetylacetonate and a heteroaromatic phthalonitrile based on1,3-quinolinediol and 4-nitrophthalonitrile and an aromaticamine—Co₂(CO)₈ (44 mg, 0.121 mmol), Cu acetylacetonate (32 mg, 0.121mmol), heteroaromatic phthalonitrile (1.00 g, 2.42 mmol), p-BPAS (50 mg,5 wt %) and 10 ml of chloroform were added to a 50 ml round bottomedflask. The homogeneous mixture was allowed to stir for 1 h before thesolvent was removed under reduced pressure. The mixture was vacuum driedto yield a dark solid.

EXAMPLE 48

Thermal conversion of 1/20 molar mixture of octacarbonyldicobalt, copperacetylacetonate and a heteroaromatic phthalonitrile based on1,3-quinolinediol and 4-nitrophthalonitrile and an aromatic amine tocarbon nanotube-cobalt nanoparticle composition—The mixture from Example47 (100 mg) was heated on a hot plate to 300° C. until the monomerpolymerized (10 min). A piece of the aforementioned polymer (50 mg) washeated in a TGA chamber under nitrogen at 10° C./min to 1000° C.resulting in a shaped composition and a char yield of 73%. X-ray studiesconfirm the presence of carbon nanotubes-cobalt-copper nanoparticles inthe carbon composition. The x-ray diffraction study showed the fourcharacteristic reflections [(002), (100), (004), and (110)] values forcrystalline carbon nanotubes and the pattern for cobalt and coppernanoparticles

EXAMPLE 49

Synthesis of 1/40 molar mixture of octacarbonyldicobalt and a 2:1oligomeric heteroaromatic phthalonitrile based on bisphenol A and2,5-dibromothiophene—Co₂(CO)₈ (11 mg, 0.032 mmol), heteroaromaticphthalonitrile (1.00 g, 1.26 mmol) and 10 ml of methylene chloride wereadded to a 50 ml round bottomed flask. The homogeneous mixture wasallowed to stir for 1 h before the solvent was removed under reducedpressure. The mixture was vacuum dried to yield a dark solid.

EXAMPLE 50

Thermal conversion of 1/40 molar mixture of octacarbonyldicobalt and a2:1 oligomeric heteroaromatic phthalonitrile based on bisphenol A and2,5-dibromothiophene to carbon nanotube-cobalt nanoparticlecomposition—The mixture from Example 49 (50 mg) was heated in a TGAchamber under nitrogen at 10° C./min to 1000° C. resulting in a shapedcomposition and a char yield of 83%. X-ray studies confirm the presenceof carbon nanotubes-cobalt nanoparticles in the carbon composition. Thex-ray diffraction study showed the four characteristic reflections[(002), (100), (004), and (110)] values for crystalline carbon nanotubesand the pattern for cobalt nanoparticles

EXAMPLE 51

Synthesis of 1/40 molar mixture of octacarbonyldicobalt, silver (I)oxide and a 2:1 oligomeric heteroaromatic phthalonitrile based onbisphenol A and 2,5-dibromothiophene—Co₂(CO)₈ (11 mg, 0.032 mmol), Ag₂O(7.3 mg, 0.032 mmol) heteroaromatic phthalonitrile (1.00 g, 1.26 mmol)and 10 ml of methylene chloride were added to a 50 ml round bottomedflask. The homogeneous mixture was allowed to stir for 1 h before thesolvent was removed under reduced pressure. The mixture was vacuum driedto yield a dark solid.

EXAMPLE 52

Thermal conversion of 1/40 molar mixture of octacarbonyldicobalt, silver(I) oxide and a 2:1 oligomeric heteroaromatic phthalonitrile based onbisphenol A and 2,5-dibromothiophene to carbon nanotube-cobaltnanoparticle composition—The mixture from Example 51 (50 mg) was heatedin a TGA chamber under nitrogen at 10° C./min to 1000° C. resulting in ashaped composition and a char yield of 77%. X-ray studies confirm thepresence of carbon nanotubes-cobalt-silver nanoparticles in the carboncomposition. The x-ray diffraction study showed the four characteristicreflections [(002), (100), (004), and (110)] values for crystallinecarbon nanotubes and the pattern for cobalt and silver nanoparticles

EXAMPLE 53

Oxidative purification of a carbon nanotube-cobalt nanoparticlecomposition derived from a 1/40 molar mixture of octacarbonyldicobalt,silver (I) oxide and a 2:1 oligomeric heteroaromatic phthalonitrilebased on bisphenol A and 2,5-dibromothiophene—The carbonnanotube-cobalt-silver nanoparticle composition from Example 54 (100 mg)was heated under air in a muffle furnace at 400° C. for 2 h resulting ina weight loss of 65%. X-ray studies confirm a reduction in the amorphouscarbon and the presence of carbon nanotubes-cobalt oxide-silver oxidenanoparticles in the carbon composition.

EXAMPLE 54

Oxidative purification of a carbon nanotube-iron nanoparticlecomposition derived from a 1/40 molar mixture of iron carbonyl, andheteroaromatic phthalonitrile based on 1,3-quinolinediol and4-nitrophthalonitrile—The carbon nanotube-iron nanoparticle compositionfrom Example 53 (200 mg) was heated under air in a muffle furnace at440° C. for 6 h resulting in a weight loss of 55%. X-ray studies confirma reduction in the amorphous carbon and the presence of carbonnanotubes-iron oxide nanoparticles in the carbon composition.

Obviously, many modifications and variations are possible in light ofthe above teachings. It is therefore to be understood that the claimedsubject matter may be practiced otherwise than as specificallydescribed. Any reference to claim elements in the singular, e.g., usingthe articles “a,” “an,” “the,” or “said” is not construed as limitingthe element to the singular.

1. An oligomer having the formula:

wherein M is a metal or H; wherein n is an integer greater than or equalto 1; wherein Ar¹ and Ar² are independently selected aromatic- orheterocyclic-containing groups; and wherein Ar¹, Ar², or both areheteroaromatic or heterocyclic groups containing a nitrogen, sulfur, oroxygen heteroatom.
 2. The oligomer of claim 1, wherein theheteroaromatic or heterocyclic group is a single heteroaromatic ring oris two or more fused aromatic rings containing at least one heteroatomin the fused aromatic rings.
 3. The oligomer of claim 1, wherein n is 1or
 2. 4. The oligomer of claim 1, wherein n is greater than or equal to2.
 5. The oligomer of claim 1, wherein the compound is


6. The oligomer of claim 1, wherein the compound is